Traduttore traditore. That was a favorite saying of one of my college Russian professors. It means "the translator is a traitor." Or at least I think that's what it means. I don't speak Italian.
I almost never read science fiction in translation from another language. And the main reason is that most science fiction is written in English. If you can read English, as many readers of this blog can, then you automatically have access to 90+% of the world's published science fiction. There are a few exceptions -- there has long been a thriving parallel world of Russian science fiction -- but most science fiction remains stubbornly Anglophone.
An exception is The Three-Body Problem by Liu Cixin, translated into English by Ken Liu. I'm only about halfway through, but I do have some preliminary thoughts. The very beginning of the novel takes place during the Cultural Revolution -- it offers a fascinating and chilling portrait of a world in which correct political thought overrules all other considerations. The novel takes up some interesting metaphysical questions, but I haven't gotten far enough to see if it delivers what it promises here. And whatever you do, don't read the teaser on the book jacket -- it gives away a major surprise element of the plot!
The prose does seem stilted in a few places -- I don't know if that's from the original Chinese, or if it is a relic of the translation. But outside of these few spots, most of the book reads very smoothly. My son, who studied Chinese, tells me that the language is particularly well-suited for puns, which of course don't translate well at all. But most science fiction is written in a very straightforward style (think Isaac Asimov) and so does not present the same sort of translation problems that would be encountered, e.g., in translating poetry. Although I suspect a writer like Ray Bradbury wouldn't translate easily.